Add lowering from AST to logical plan for graph MATCH

[jpschorr]

This PR:

• Builds on Add support for GPML-style graph query parsing #548 and Add GPML logical plan and plan -> evaluator. #549
• enables the experimental conformance tests which include the GPML tests
• Refactors some types and traits into non-pub modules.
• Fixes some minor graph evaluation edge case bugs
• Adds lowering from the AST to the logical plan for graph match stuff.

---

Some of the graph conformance tests are still failing; These are largely tests that specify only an edge and have implicit start and end nodes (e.g., ( graph MATCH -> )).

The current grammar cannot parse such a construction. I intend to tackle this in follow-up work, perhaps including modernizing the grammar to follow SQL '23.

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

Conformance comparison report

	Base (3d4e27b)	3d4e27b	+/-
% Passing	87.15%	86.85%	-0.31%
✅ Passing	5603	5731	128
❌ Failing	826	868	42
🔶 Ignored	0	0	0
Total Tests	6429	6599	170

Number passing in both: 5603

Number failing in both: 826

Number passing in Base (3d4e27b) but now fail: 0

Number failing in Base (3d4e27b) but now pass: 0

[codecov]

Codecov Report

Attention: Patch coverage is 83.94649% with 48 lines in your changes missing coverage. Please review.

Project coverage is 81.93%. Comparing base (2bf9bbf) to head (e0a6101).
Report is 1 commits behind head on feat-plan-gpml.

Files with missing lines	Patch %	Lines
partiql-logical-planner/src/graph.rs	80.09%	34 Missing and 9 partials ⚠️
partiql-logical-planner/src/lower.rs	75.00%	3 Missing and 1 partial ⚠️
partiql-eval/src/plan.rs	96.00%	1 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##           feat-plan-gpml     #551      +/-   ##
==================================================
+ Coverage           81.56%   81.93%   +0.36%     
==================================================
  Files                 107      108       +1     
  Lines               22487    22723     +236     
  Branches            22487    22723     +236     
==================================================
+ Hits                18342    18618     +276     
+ Misses               3632     3567      -65     
- Partials              513      538      +25     

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[alancai98]

is this TODO still relevant?

[jpschorr]

Yes